From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63A15C76186 for ; Mon, 29 Jul 2019 20:04:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2CBF7205F4 for ; Mon, 29 Jul 2019 20:04:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SN8oRnKN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729899AbfG2UDy (ORCPT ); Mon, 29 Jul 2019 16:03:54 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50528 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390053AbfG2TqD (ORCPT ); Mon, 29 Jul 2019 15:46:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=arjAFJhp7h7y5/Rhm9vbvSAfd/7R4cvilJkOjN26CHs=; b=SN8oRnKNdwiYVQc5vagAqPbm+ nhxf5g6kbo+jKIaT6WgKBcfCA8UcqWtLb5tfvvfPr0DnCW4uPrM2lOtfI2Fox14O7d9d/Bl0Hvb2X OQBjh31Ya9sBlmKEvwiddNcyOKFWtTMswOB+Iobowmyi48gpJUkxMGD1ABNN7QrOWfmR4/zORTOjr ePtw/rxjoexYv6kZpzSRnYMWA6r+WBQxmFTho+98N2VB2Z6XXL5C1yglMxjq2KMDaoGzdMBu049b2 c8uWJ1RE7Qal8WtUdrLdzFAuyUPkktjOOqxfaZPtxSJvHqAhYYRA9B+mApJCjR2WJH+7hqvKtJp6r gwnx5hhLg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hsBaj-0006AY-6P; Mon, 29 Jul 2019 19:45:53 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8C45020C9B161; Mon, 29 Jul 2019 21:45:50 +0200 (CEST) Date: Mon, 29 Jul 2019 21:45:50 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: LKML , x86@kernel.org, Steven Rostedt , Sebastian Siewior , Anna-Maria Gleixner , Arnaldo Carvalho de Melo , Jiri Olsa , Paolo Bonzini , Juergen Gross Subject: Re: [patch 00/12] (hr)timers: Prepare for PREEMPT_RT support Message-ID: <20190729194550.GP31398@hirez.programming.kicks-ass.net> References: <20190726183048.982726647@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190726183048.982726647@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 26, 2019 at 08:30:48PM +0200, Thomas Gleixner wrote: > The following series brings the bulk of PREEMPT_RT specific changes for the > (hr)timer code: > > - Handle timer deletion correctly under RT to avoid priority inversion > and life locks > > This mechanism might be useful for VMs as well when a vCPU > executing a timer callback gets scheduled out and on another vCPU > del_timer_sync() or hrtimer_cancel() is invoked. > > The mitigation would only work when paravirt spinlocks are > enabled. I've not implemented that, as I don't know whether this is a > real world issue. I just noticed that it is basically the same > problem. Adding it would be trivial. > > - Prepare for moving most hrtimer callbacks into softirq context and mark > timers which need to expire in hard interrupt context even on RT so > they don't get moved. > Acked-by: Peter Zijlstra (Intel)